The work proposed this year will focus heavily on the assessment of chemosensory functioning in the olfactory and common modalities of human beings. A reflex interruption of inhalation in response to sniffing an irritant may offer the first objective index of chemosensory functioning. The threshold for the reflex is higher in smokers than in non-smokers and is particularly high in male smokers. Experiments will explore whether such differences reflect neural factors or non-neural factors, such as nasal patency and mucostasis. Psychophysical measures of interest for the assessment of chemosensory status will include absolute sensitivity to odorants and irritants and reaction time. These will also be used to assess the influence of both short-term and long-term occupational exposure to formaldehyde on chemosensory functioning. The psychophysical properties of formaldehyde itself will also receive attention in experiments performed in a large environmental chamber that will allow natural exposure to this notable contaminant. Finally, experiments on the influence of temporal lobe disturbances on olfactory processing will be continued. This aspect of the project has already revealed substantial differences between peripheral and central neural determinants of olfactory performance.